ibn al-haytham, abu 'ali al-hasan

(ĭb'ən ěl-hī'thəm) Arab mathematician who wrote almost 100 works on mathematics, astronomy, philosophy, and medicine, but who is best known for his book on optics, which became very influential in Europe after it was translated in the 13th century. It contained a detailed description of the eye and disproved the older Greek idea that vision is the result of the eye sending out rays to the object being looked at.